1. Field of Invention
This invention relates to digital information compression (including data, image, video, audio and multimedia among others) and decompression with medical, seismographic, telemetric, astronomic, meteorological, surveillance and monitoring applications among others, and involves a method and apparatus which can perform all these types of compression in either a lossless or lossy mode or some combination of both and utilizes a universal, asymptotically optimal multilevel algorithm based on the Lawrence algorithm.
2. Description of Prior Art
Heretofore, the field of information compression has been divided into techniques which perform data or image or video or speech or other kinds of digital signal compression. It has been further divided into techniques which are either lossless .sup.i.e. the decompressed data is exactly the same as the original data or lossy .sup.i.e. the decompressed data is similar to but is not exactly the same as the original data. Data compression, which involves computer programs and files among other things, usually requires lossless compression although it is possible to foresee applications in which text files, for instance, might not be reproduced with total accuracy and still remain intelligible. Image and video compression, on the other hand, have usually been associated with lossy compression since visual information remains intelligible even after it has been degraded to some extent and lossless methods have not been able to produce the amount of compression required. However, there are some applications in the medical and military fields, for instance, where lossless image and video compression is highly desirable. For example, artifacts, associated with lossy compression, could show up and be interpreted incorrectly as having medical significance in X-rays, CAT-scans, MRI-scans, and PET-scans.
There are some techniques which are only appropriate for image or video compression and some techniques which can be modifier to do both. In general data compression techniques have not been found to be appropriate for image or video compression and vice versa. Audio compression has usually been of the lossy variety, and a wide range of other digital signals such as signals from seismographic, telemetric, astronomic, meteorological, surveillance and monitoring data collection devices have been compressed either lossily or losslessly.